Combustion chamber of a gas turbine with improved acoustic damping

ABSTRACT

A combustion chamber of a gas turbine includes an optimized arrangement of acoustic dampers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to European Patent Application 13188229.2 filed Oct. 11, 2013, the contents of which are hereby incorporated in its entirety.

TECHNICAL FIELD

The invention is related to the acoustic damping of combustions dynamics. Combustion dynamics in the meaning of this application comprises pulsations, acoustic oscillations, pressure and velocity fluctuations and what is called in the everyday language noise. The terms “combustions dynamics” and “noise” are sometimes used synonymously.

BACKGROUND

Combustion dynamics occur for example in gas turbines at different places or chambers, where combustion dynamics occur. Examples for such places or chambers are the combustor chamber, a mixing chamber, a plenum and air channels. For reasons of simplification subsequently the term “chamber” is used and comprises all locations where combustion dynamics occur. In these chambers a gas (for example a mixture of fuel and air or exhaust gas) flows with high velocity which causes combustion dynamics. Burning air and fuel in the combustion chamber causes further combustion dynamics.

To reduce these combustion dynamics it is well known in the art, to install acoustic damping devices like a Helmholtz resonator, a half-wave tube, a quarter-wave tube or other types of damping devices with or without flow through of gas.

These acoustic damping devices have one or more resonance frequencies. If under operation of the gas turbine the combustions dynamics stimulate the resonance frequencies of the acoustic damping devices, the combustion dynamics are reduced or damped.

SUMMARY

It is an objective of the claimed invention to place the acoustic damping devices to achieve optimal damping under given constraints.

This objective is achieved by a chamber of a gas turbine with combustion dynamics, comprising several acoustic dampers circumferentially being arranged around an opening of the chamber by arranging at least two acoustic dampers of the same type in one section of the chamber covering an angle of 60°. Advantageously the acoustic dampers are arranged in an annular ring around the opening.

By arranging the dampers in this manner the combustion dynamics of the gas turbine in operation could be damped more effectively.

It is advantageous to place in one section of the chamber covering an angle of 60° at uppermost six (6) acoustic dampers

Further it is possible to place in one section one, two, three, four, five or six types of acoustic dampers. All dampers that are tuned to the same damping frequency, for example 90 Hz+−2%, are of the same type. This means that Helmholtz dampers and quarter-wave dampers may be of the same type in the meaning of the claimed invention.

A further advantageous embodiment is characterized in that an angle between two adjacent acoustic dampers is equal to or greater than 10°.

Another advantageous embodiment is characterized in that in one section of the chamber at least six burners and uppermost ten burners are arranged. Advantageously these burners are selected from the group of dual fuel burners for gas turbines.

Arranging the dampers of each section of an opening in this way, has led to improved reduction of combustion dynamics.

The applicable acoustic dampers are not restricted to Helmholtz dampers with one or more damping volumes but may be half-wave length dampers, quarter-wave length dampers and other acoustic dampers with one or more damping volumes.

The claimed invention may be applied to combustion chambers, mixing chambers, a plenum and/or air channels of a gas turbine.

Further advantages and details of the claimed invention are subsequently described in conjunction with the drawings and their description.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures show:

FIG. 1 a first embodiment of the claimed invention,

FIG. 2 a second embodiment of the claimed invention.

Both figures illustrate a front view of a combustor chamber 10 of a gas turbine. The combustor chamber 10 comprises an opening 12 covering a center angle of 360°. This center angle is divided in six sections 1, 2, 3, 4, 5, and 6 each covering an angle α of 60.

Distributed in the claimed manner are several types T1, T2, T3, T4, T4 and T6 of acoustic dampers in an annular ring 14. The type T1 for example may be tuned to a damping frequency of 90 Hz, whereas the type T2 for example may be tuned to a damping frequency of 100 Hz and so on.

In both figures dual fuel burners B1 for gas turbines are arranged in each section 1, 2, 3, 4, 5, 6 in the annular ring 14 besides the several types of acoustic dampers T1, T2, T3, T4, T5 and T6. Advantageously depending on the number of acoustic dampers in one section between six and ten burners are arranged in each section. In section 4 of FIG. 1 and FIG. 2 for example, eight burners B1 are arranged. For the sake of lucidity, in sections 1, 2, 3, 5 and 6, only one burner B1 is marked with an own reference numeral.

In FIG. 1 the sections 4, 5 and 6, each comprise in clockwise direction one T4-, T5-, T1- and T3-type damper.

In FIG. 2 for example the sections 3, 4 and 5, each comprise in clockwise direction a T3, a T1-, a T3- and a T5-type damper.

In FIG. 2 for example the sections 6, 1 and 3, each comprise in clockwise direction a T6, a T1-, a T6- and a T5-type damper.

By adapting the patterns of dampers in each section to a specific gas turbine a great reduction of combustion dynamics may be achieved. 

1. A chamber of a gas turbine comprising several acoustic dampers circumferentially arranged around an opening of the chamber, wherein in one section of the chamber covering an angle (α) of 60° at least two acoustic dampers are arranged.
 2. The chamber according to claim 1, wherein in one section of the chamber covering an angle (α) of 60° at uppermost six acoustic dampers are arranged.
 3. The chamber according to claim 1, wherein in one section up to six types of acoustic dampers are arranged.
 4. The chamber according to claim 1, wherein in an angle (β) between two adjacent acoustic dampers is equal to or greater than 10°.
 5. The chamber according to claim 1, wherein in one section of the chamber at least six burners and uppermost ten burners are arranged.
 6. The chamber according to claim 1, wherein the acoustic dampers are selected from a group comprising Helmholtz dampers, half-wave length dampers, quarter-wave length dampers.
 7. The chamber according to claim 1, wherein the acoustic dampers comprise one or more damping volumes.
 8. The chamber according to claim 1, further comprising a combustion chamber, a mixing chamber, a plenum and/or air channels of a gas turbine. 